This invention relates to recording and playback of multi-channel digital audio having different sampling rates for different channels.
Commonly assigned McPherson et al. U.S. patent application Ser. No. 09/066,042, filed Apr. 24, 1998 and McPherson et al. U.S. patent application Ser. No. 09/066,041, filed Apr. 24, 1998 are incorporated herein by reference.
Technology of the type used for software carriers such as the Digital Versatile Disc ("DVD") makes it economically viable to provide recording media containing greatly enhanced audio information. For example, it is possible to provide digital audio recordings on software carriers having six channels of digital audio to be played by six-channel audio systems. The typical six-channel audio system has a front left channel, a front center channel, a front right channel, a rear left channel, a rear right channel, and a subwoofer (low frequency effect, "LFE") channel.
It is known that increased sampling rates provide better audio reproduction. However, sampling all channels of multi-channel audio at very high rates may produce more data and take up more space on the software carrier than is necessary to produce better reproduction. In addition, many potential purchasers of audio software carriers may have only two-channel stereophonic audio systems, and it may be wasteful of space on the software carrier to record the same audio programming in both six-channel and two-channel versions, especially when higher sampling rates are to be used to enhance audio reproduction quality.
In view of the foregoing, it is an object of this invention to provide methods and apparatus for recording and playing back multi-channel digital audio having different sampling rates for different channels in order to avoid recording more data than is necessary and consequently to conserve space on the software carrier.
It is another object of this invention to provide methods and apparatus for deriving from audio information recorded and played back in one format audio signals in a different format so that both formats do not have to be recorded on the software carrier.